microsoft/garnet · error · TsavoriteException

{nameof(rcs.PageSizeBits)} must be between {LogSettings.kMin

Error message

{nameof(rcs.PageSizeBits)} must be between {LogSettings.kMinPageSizeBits} and {LogSettings.kMaxPageSizeBits}

What it means

Constructor validation for the read cache: rcs.PageSizeBits must be in [kMinPageSizeBits, kMaxPageSizeBits] = [12, 27] (4KiB..128MiB), the same bounds as the main log page size. The read cache uses the same page machinery.

Source

Thrown at libs/storage/Tsavorite/cs/src/core/Allocator/AllocatorBase.cs:569

            if (logSettings.PageSizeBits < PageHeader.SizeBits)
                throw new TsavoriteException($"{nameof(logSettings.PageSizeBits)} must be >= PageHeader.SizeBits {PageHeader.SizeBits}");
            if (logSettings.PageCount > MemoryUtils.ArrayMaxLength)
                throw new TsavoriteException($"{nameof(logSettings.PageCount)} must be less than or equal to the maximum array length ({MemoryUtils.ArrayMaxLength})");
            if (logSettings.SegmentSizeBits < LogSettings.kMinMainLogSegmentSizeBits || logSettings.SegmentSizeBits > LogSettings.kMaxSegmentSizeBits)
                throw new TsavoriteException($"{nameof(logSettings.SegmentSizeBits)} must be between {LogSettings.kMinMainLogSegmentSizeBits} and {LogSettings.kMaxSegmentSizeBits}");
            if (logSettings.MemorySize != 0 && (logSettings.MemorySize < 1L << LogSettings.kMinMemorySizeBits || logSettings.MemorySize > 1L << LogSettings.kMaxMemorySizeBits))
                throw new TsavoriteException($"{nameof(logSettings.MemorySize)} must be between {1L << LogSettings.kMinMemorySizeBits} and {1L << LogSettings.kMaxMemorySizeBits}, or may be 0 for ReadOnly TsavoriteLog");
            if ((logSettings.MemorySize != 0) && (logSettings.MemorySize < (1L << logSettings.PageSizeBits) * LogSettings.kMinPageCount))
                throw new TsavoriteException($"{nameof(logSettings.MemorySize)} must be at least {LogSettings.kMinPageCount}x the page size ({1L << logSettings.PageSizeBits})");
            if (logSettings.MutableFraction < 0.0 || logSettings.MutableFraction > 1.0)
                throw new TsavoriteException($"{nameof(logSettings.MutableFraction)} must be >= 0.0 and <= 1.0");
            if (logSettings.ReadCacheSettings is not null)
            {
                var rcs = logSettings.ReadCacheSettings;
                if (rcs.PageCount == 0 && rcs.MemorySize == 0)
                    throw new TsavoriteException($"{nameof(rcs.PageCount)} or {nameof(rcs.MemorySize)} must be specified");
                if (rcs.PageSizeBits < LogSettings.kMinPageSizeBits || rcs.PageSizeBits > LogSettings.kMaxPageSizeBits)
                    throw new TsavoriteException($"{nameof(rcs.PageSizeBits)} must be between {LogSettings.kMinPageSizeBits} and {LogSettings.kMaxPageSizeBits}");
                if (rcs.PageCount > MemoryUtils.ArrayMaxLength)
                    throw new TsavoriteException($"{nameof(rcs.PageCount)} must be less than or equal to the maximum array length ({MemoryUtils.ArrayMaxLength})");
                if (rcs.MemorySize != 0 && (rcs.MemorySize < 1L << LogSettings.kMinMemorySizeBits || rcs.MemorySize > 1L << LogSettings.kMaxMemorySizeBits))
                    throw new TsavoriteException($"{nameof(rcs.MemorySize)} must be between {1L << LogSettings.kMinMemorySizeBits} and {1L << LogSettings.kMaxMemorySizeBits}");
                if ((rcs.MemorySize != 0) && (rcs.MemorySize < (1L << rcs.PageSizeBits) * 2))
                    throw new TsavoriteException($"{nameof(logSettings.MemorySize)} must be at least twice the page size ({1L << rcs.PageSizeBits})");
                if (rcs.SecondChanceFraction < 0.0 || rcs.SecondChanceFraction > 1.0)
                    throw new TsavoriteException($"{rcs.SecondChanceFraction} must be >= 0.0 and <= 1.0");
            }

            if (logSettings.MaxInlineKeySize < LogSettings.MinMaxInlineSize || logSettings.MaxInlineKeySize > LogSettings.MaxInlineKeySizeLimit)
                throw new TsavoriteException($"{nameof(logSettings.MaxInlineKeySize)} must be between {LogSettings.MinMaxInlineSize} and {LogSettings.MaxInlineKeySizeLimit}");
            if (logSettings.MaxInlineValueSize < LogSettings.MinMaxInlineSize || logSettings.MaxInlineValueSize > LogSettings.MaxInlineValueSizeLimit)
                throw new TsavoriteException($"{nameof(logSettings.MaxInlineValueSize)} must be between {LogSettings.MinMaxInlineSize} and {LogSettings.MaxInlineValueSizeLimit}");

            this.logger = logger;
            if (logSettings.LogDevice == null)
                throw new TsavoriteException("LogSettings.LogDevice needs to be specified (e.g., use Devices.CreateLogDevice, AzureStorageDevice, or NullDevice)");

View on GitHub (pinned to 951b0fc683)

Solutions

Set rcs.PageSizeBits within [12, 27]; matching the main log's PageSizeBits is a sensible default.
If unsure, omit the field and use a value like 25 (32MiB) consistent with the main log.

Example fix

// before
rcs.PageSizeBits = 10;
// after
rcs.PageSizeBits = logSettings.PageSizeBits; // mirror main log, within [12,27]

Defensive patterns

Strategy: validation

Validate before calling

const int MinPageBits = 12, MaxPageBits = 27;
if (logSettings.ReadCacheSettings is { } rcs && (rcs.PageSizeBits < MinPageBits || rcs.PageSizeBits > MaxPageBits))
    rcs.PageSizeBits = Math.Clamp(rcs.PageSizeBits, MinPageBits, MaxPageBits);

Try / catch

try { new TsavoriteKV<K,V>(logSettings, ...); }
catch (TsavoriteException ex) when (ex.Message.Contains("rcs.PageSizeBits") && ex.Message.Contains("between"))
{ /* clamp rcs.PageSizeBits to [12,27] and recreate */ }

Prevention

Mirror the main log's PageSizeBits into the read cache by default.
Validate read-cache page size in the same helper that validates the main log.

When it happens

Trigger: Setting `ReadCacheSettings.PageSizeBits` below 12 or above 27 when enabling the read cache.

Common situations: Forgetting to set rcs.PageSizeBits and assuming a default (there is no constructor default guaranteed); tuning read-cache pages below the floor.

Related errors

AI-assisted analysis of microsoft/garnet@951b0fc683 (2026-08-13). Data as JSON: /api/errors/ca27a025ba5be17b. Report an issue: GitHub.